Why can't I use Ctrl+` as prefix in tmux? I am able to use ` as prefix in tmux. unbind C-b set-option -g prefix ` bind-key ` send-prefix But that key is very useful for other purposes, so I am trying to use Control+that_key and that doesn't work. unbind C-b set-option -g prefix C-` bind-key C-` send-prefix gives me: .tmux.conf: bad key: C-` .tmux.conf: unknown key: C-` Am I doing something wrong? Or is this not allowed for some reason?

As noted by @Kusalananda in the comments (and this mostly unrelated Stack Overflow answer), `Ctrl`+``` typically returns an ASCII `NUL`/`0` in most terminals.

`Ctrl`+`Space` and (very oddly) `Ctrl`+`2` do the same.

@Kusalananda also mentioned a Vim trick that appears to also work in Tmux:


set-option -g prefix C-@


Which I've confirmed works. Note that, as a result, `Ctrl`+`Space` and `Ctrl`+`2` will then also work as prefix, assuming that nothing else in the OS or terminal captures them instead.